Position detection system and control method of position detection system

ABSTRACT

A projection system includes a light emitting apparatus that emits detection light to a detection area for detecting indication positions of indicators, and a projector that detects the indication positions of the indicators in the detection area. The projector includes an imaging portion that captures an image of the detection area, and a position detection portion that detects at least one of an image of light generated by the indicator and an image of the detection light reflected on the indicator from data of a captured image of the imaging portion, and discriminates and detects the indication positions of the indicator and the indicator based on light emission timings of the indicator and the light emitting apparatus.

This is a Continuation of U.S. application Ser. No. 14/598,795 filedJan. 16, 2015, which claims priority to Japanese Patent Application Nos.2014-008627 (filed Jan. 21, 2014) and 2014-062102 (filed Mar. 25, 2014).The disclosure of the price applications are hereby incorporated byreference herein in their entirety.

BACKGROUND

1. Technical Field

The present invention relates to a position detection system and acontrol method of the position detection system.

2. Related Art

In the related art, a technique of detecting a position of an indicatorin a detection area by detecting variation ranges of light amountdistributions respectively obtained from a plurality of sensor units hasbeen known (for example, Japanese Patent No. 4757144).

If an indication position of an indicator is optically detected, it isnot considered that light evenly reaches all the locations in adetection area, and this influences the detection accuracy. At thispoint, the configuration of Japanese Patent No. 4757144 is to enhancethe accuracy by calculating distribution of light amounts, but, forexample, when the indication position is detected by capturing an imageof the detection area, the method cannot be applied. In addition, whenthe indication positions of a plurality of indicators in different,kinds are detected, a plurality of sensors have to be further provided,and the size of the apparatus configuration increases.

SUMMARY

An advantage of some aspects of the invention is to provide a positiondetection system that can accurately detect indication positions ofdifferent kinds of indicators by using the data of the captured imageeven if the configuration is simple, and a control method of theposition detection system.

An aspect of the invention is directed to a position detection systemincluding: a light emitting apparatus that emits detection light to adetection area for detecting indication positions of indicators; and aposition detection apparatus that detects the indication positions ofthe indicators in the detection area, in which the position detectionapparatus includes an imaging portion that captures an image of thedetection area, and a position detection portion that detects at leastone of an image of light generated by a first indicator of theindicators and an image of the detection light reflected on a secondindicator of the indicators from data of a captured image of the imagingportion, and discriminates and detects the indication positions of thefirst indicator and the second indicator based on light emission timingsof the first indicator and the light emitting apparatus.

With this configuration, at least one of an image of light generated bya first indicator of the indicators and an image of the detection lightreflected on a second indicator of the indicators from the data of thecaptured image is detected. In addition, the indication positions of thefirst indicator and the second indicator are discriminated and detectedbased on light emission timings of the first indicator and the lightemitting apparatus. Therefore, it is possible to accurately detectindication positions of different kinds of indicators by using the dataof the captured image even if the configuration is simple.

Another aspect of the invention is directed to the position detectionsystem of the configuration described above, wherein the positiondetection portion detects a position of a bright spot taken in the dataof the captured image after the light emitting apparatus is turned off,as the indication position of the first indicator.

With this configuration, it is possible to easily discriminate the firstindicator and the second indicator, and to accurately detect indicationpositions of different kinds of indicators.

Still another aspect of the invention is directed to the positiondetection system of the configuration described above, wherein theposition detection portion determines light that the plurality of firstindicators turn on and off according to identification informationallocated to the respective first indicators based on the data of thecaptured image, and discriminates and detect the indication positions ofthe plurality of first indicators.

With this configuration, if the plurality of first indicators areprovided, it is possible to discriminate and detect the indicationpositions of the respective first indicators.

Yet another aspect of the invention is directed to the positiondetection system of the configuration described above, wherein theposition detection apparatus includes a first transmitting portion thattransmits a synchronization signal for informing lighting timing of thefirst indicator, and a second transmitting portion that transmits asignal for informing timing at which the detection light is emitted tothe light emitting apparatus.

With this configuration, the position detection apparatus can capture animage of the detection area by the imaging portion in synchronizationwith lighting timings of the first indicator and the light emittingapparatus. Therefore, it is possible to detect the indication positionsof the first and second indicators.

Still yet another aspect of the invention is directed to a controlmethod of a position detection system that includes a light emittingapparatus that emits detection light to a detection area for detectingindication positions of indicators and a position detection apparatusthat detects the indication positions of the indicators in the detectionarea, including: capturing an image of the detection area by an imagingportion; and detecting at least one of an image of light generated by afirst indicator of the indicators and an image of the detection lightreflected on a second indicator of the indicators from data of acaptured image of the imaging portion, and discriminating and detectingthe indication positions of the first indicator and the second indicatorbased on light emission timings of the first indicator and the lightemitting apparatus.

With this configuration, at least one of an image of light generated bya first indicator of the indicators and an image of the detection lightreflected on a second indicator of the indicators from the data of thecaptured image is detected. In addition, the indication positions of thefirst indicator and the second indicator are discriminated and detectedbased on light emission timings of the first indicator and the lightemitting apparatus. Therefore, it is possible to accurately detectindication positions of different kinds of indicators by using the dataof the captured image even if the configuration is simple.

According to the aspects of the invention, it is possible to accuratelydetect indication positions of different kinds of indicators by usingthe data of the captured image even if the configuration is simple.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described with reference to the accompanyingdrawings, wherein like numbers reference like elements.

FIG. 1 is a diagram schematically illustrating a configuration of aprojection system.

FIG. 2 is a functional block diagram of the projection system.

FIG. 3 is a flow chart illustrating an operation of a projector.

FIG. 4A illustrates a state of detecting an indication position of apen-type indicator, and FIG. 4B illustrates state of detecting theindication position of a finger as the indicator.

FIG. 5 is a diagram illustrating an example of an auto calibrationimage.

FIG. 6 is a diagram illustrating an example of data of a captured imagecaptured by an imaging portion.

FIG. 7 is a diagram illustrating an example of a calibration datamanaging table.

FIG. 8 is a diagram illustrating an example of a manual calibrationimage.

FIG. 9 is a flow chart illustrating details of a background imagecreating process.

FIG. 10 is a diagram illustrating an example of a mask image.

FIG. 11 is a diagram illustrating a method of creating the mask image.

FIG. 12 is a diagram illustrating an example of data of a firstbackground image.

FIG. 13 is a diagram illustrating an example of data of a secondbackground image.

FIG. 14 is a flow chart illustrating details of an indication positiondetecting process.

FIG. 15A is a diagram illustrating concentration threshold value whichis set in combination with the mask image, and FIG. 15B is a diagramillustrating concentration threshold values in points A to D illustratedin FIG. 15A.

FIG. 16 is a diagram illustrating an example of the light source noisedata.

FIG. 17 is a diagram illustrating light emission timings of a projector,an indicator, and the light emitting apparatus.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, embodiments of the invention are described with referenceto the accompanying drawings.

FIG. 1 is a diagram illustrating a configuration of a projection system1 according to the embodiment to which the invention is applied. Theprojection system 1 includes a projector 10 (position detectionapparatus) installed on the upper side of a screen SC (projectionsurface) and a light emitting apparatus (light source portion) 60installed on the upper side of the screen SC.

The projector 10 is installed right above or on the obliquely upper sideof the screen SC, and projects an image toward the screen SC on theobliquely lower side. In addition, the screen SC described in thepresent embodiment is a flat board or a screen fixed on a surface of awall or stood on a floor. The invention is not limited to this example,and a surface of a wall can be used as the screen SC. In this case, theprojector 10 and the light emitting apparatus 60 may be mounted on theupper portion of the surface of the wall used as the screen SC.

The projector 10 is connected to an external image supplying apparatussuch as a personal computer (PC), a video reproducing apparatus, or aMID reproducing apparatus, and projects an image on the screen SC basedon the analog image signal or the digital image data supplied from theimage supplying apparatus. In addition, the projector 10 may read imagedata stored in the embedded storage portion 110 (FIG. 2) or externallyconnected recording medium, and display an image on the screen SC basedon the image data.

The light emitting apparatus 60 has a light source portion 61 (FIG. 2)formed of a solid light source and diffuses and emits (applies) light(infrared light according to the present embodiment) generated by thelight source portion 61 along the screen SC. The emission scope of thelight emitting apparatus 60 is illustrated by an angle θ in FIG. 1. Thelight emitting apparatus 60 is installed above from the upper end of thescreen SC and downwardly emits the light in the scope of the angle θ,and the light forms a light layer along the screen SC. The angle θaccording to the present embodiment reaches almost 180°, and the lightlayer is formed on nearly the entire screen SC. It is preferable thatthe front surface of the screen SC and the light layer are close to eachother, and the distance between the front surface of the screen SC andthe light layer according to the present embodiment is roughly in thescope of 1 mm to 10 mm.

When the indication operation is performed on the screen SC, theprojection system 1 detects the indication position by the projector 10.

The indicator used in the indication operation can use a pen-typeindicator 70. Since an operating switch 75 (FIG. 2) that operates whenbeing pressed is embedded on a tip portion 71, of the indicator 70, ifan operation of pressing the tip portion 71 on the wall or the screen SCis performed, the operating switch 75 is turned on. A user holds abar-shaped shaft portion 72 in his or her hand and operates theindicator 70 so that the tip portion 71 is in contact with the screen SCor the tip portion 71 is pressed onto the screen SC. A transmitting andreceiving portion 74 (FIG. 2) that generates infrared light is providedon the tip portion 71. The projector 10 detects a position of the tipportion 71 as an indication position based on the infrared lightgenerated by the indicator 70.

In addition, when the position indication operation is performed by anindicator 80 which is a finger of the user, the user causes the fingerto come into contact with the screen SC. In this case, a position onwhich the indicator 80 comes into contact with the screen SC isdetected. That is, when the tip of the indicator 80 (for example,fingertip) is in contact with the screen SC, the light layer formed bythe light emitting apparatus 60 is blocked. At this point, the lightemitted by the light emitting apparatus 60 is reflected on the indicator80, and a portion of the reflected light travels from the indicator 80to the projector 10. Since the projector 10 has a function of detectingthe light from the screen SC side, that is, the light from the lowerside, with a position detection portion 50 described below, thereflected light of the indicator 80 can be detected. The projector 10detects an indication operation to the screen. SC by the indicator 80,by detecting the reflected light reflected on the indicator 80. Inaddition, the projector 10 detects the indication position indicated bythe indicator 80.

Since the light layer emitted by the light emitting apparatus 60 isclose to the screen SC, the position of the indicator 80 at which lightis reflected can be considered to be the tip or the indication positionwhich is closest to the screen. SC. Therefore, the indication positioncan be specified based on the reflected light of the indicator 80.

The projection system 1 functions as an interactive white board system,detects an indication operation performed by the user with theindicators 70 and 80, and causes the indication position to be reflectedon the projection image. Specifically, the projection system 1 performsa process of drawing a diagram or arranging a character or a symbol onthe indication position, a process of drawing a diagram along a locus ofthe indication position, a process of deleting the drawn diagram or thearranged character or symbol, or the like. In addition, the drawndiagram or the arranged character or symbol on the screen SC can bestored as image data, and can be output to an external apparatus.

Additionally, the projection system 1 may be operated as a pointingdevice by detecting the indication position, and may output coordinatesof the indication position on the image projection area at which theprojector 10 projects an image on the screen SC. In addition, aGraphical User Interface (GUI) operation may be performed by using thecoordinates.

FIG. 2 is a functional block diagram of respective portions that formthe projection system 1.

The projector 10 includes an interface (I/F) portion 11 and an imageinterface (I/F) portion 12 as interfaces for connection to an externalapparatus. The I/F portion 11 and the image I/F portion 12 includeconnectors for wired connection, and may include interface circuitscorresponding to the connectors. In addition, the I/F portion 11 and theimage I/F portion 12 may include wireless communication interfaces. Asthe connectors and interface circuits for the wired connection, aconnector or an interface circuit for the wired connection conforming toa wired LAN, IEEE1394, USB, or the like may be included. In addition, asan wireless communication interface, a connector or an interface circuitconforming to a wireless LAN, Bluetooth (registered trademark), or thelike may be included. In the image I/F portion 12, an interface forimage data such as HDMI (registered trademark) interface can be used.The image I/F portion 12 may include an interface for inputting sounddata.

The I/F portion 11 is an interface for transmitting and receivingvarious data between external apparatuses such as a PC. The I/F portion11 inputs and outputs control data relating to image projection, settingdata for setting an operation of the projector 10, coordinate data ofthe indication position detected by the projector 10, or the like. Thecontrol portion 30 described below has a function of transmitting andreceiving data with an external apparatus through the I/F portion 11.

The image I/F portion 12 is an interface for inputting digital imagedata. The projector 10 according to the present embodiment projects animage based on the digital image data input through the image I/Fportion 12. Further, the projector 10 may include a function ofprojecting an image based on the analog image signal, and in this case,the image I/F portion 12 may include an interface for an analog imageand an A/D converting circuit for converting an analog image signal intodigital image data.

The projector 10 includes a projecting portion 20 for forming an opticalimage. The projecting portion includes a light source portion 21, anoptical modulating device 22, and a projection optical system 23. Thelight source portion 21 includes a light source formed by a xenon lamp,an extra-high pressure mercury lamp, a Light Emitting Diode (LED), alaser light source, or the like. In addition, the light source portion21 may include a reflector and an auxiliary reflector for guiding lightgenerated by the light source to the optical modulating device 22.Additionally, a lens group (not illustrated) or a polarizing plate forenhancing an optical property of projected light, or a dimmer elementfor decreasing a light amount of the light generated from the lightsource on a path reaching the optical modulating device 22 may beincluded.

The optical modulating device 22 includes three transparent liquidcrystal panels, for example, corresponding to three primary colors ofRCM, and generates image light by modulating the light that penetratesthrough the liquid crystal panel. The light from the light sourceportion 21 is separated into colored beams of three colors of RGB, andthe colored beams are incident to the respective corresponding liquidcrystal panels. The colored beams that penetrate the respective liquidcrystal panels and are modulated are synthesized by a synthesis opticalsystem of a cross dichroic prism, and are emitted to the projectionoptical system 23.

The projection optical system 23 includes a lens group that guides imagelight modulated by the optical modulating device 22 in a direction ofthe screen SC, and forms an image on the screen SC. In addition, theprojection optical system 23 includes a zoom mechanism that zooms in andout of a projection image of the screen SC, and adjusts a focal point,and a focus adjusting mechanism that adjusts a focus. When the projector10 is a short focus type, a concave mirror that reflects image lighttoward the screen SC may be included in the projection optical system23.

A light source driving portion 45 that turns on the light source portion21 under the control of a control portion 33 and an optical modulatingdevice driving portion 46 that operates the optical modulating device 22under the control of the control portion 30 is connected to theprojecting portion 20. The light source driving portion 45 has afunction of switching the turning on and off of the light source portion21, and adjusting a light amount of the light source portion 21.

The projector 1 u includes an image processing system that processes animage projected by the projecting portion 20. The image processingsystem includes the control portion 30 that controls the projector 10, astorage portion 110, an operation detecting portion 17, an imageprocessing portion 40, the light source driving portion 45, and theoptical modulating device driving portion 46. In addition, a framememory 44 is connected to the image processing portion 40, and theattitude sensor 47, the emitting device driving portion (secondtransmitting portion) 48, and the position detection portion 50 areconnected to the control portion 30. These items may be included in theimage processing system.

The control portion 30 controls respective portions of the projector 10by executing a predetermined control program 111. The storage portion110 stores the control program 111 executed by the control portion 30and data processed by the control portion 30 in a non-volatile manner.The storage portion 110 stores setting screen data 115 of a screen forsetting an operation of the projector 10, and the setting data 116 forindicating contents set by using the setting screen data 115. Thestorage portion 110 further stores an auto calibration image 121 and amanual calibration image 122. Additionally, the storage portion 110stores an auto calibration data 123, a manual calibration data 124, aninitial correction data 125, and a manual correction data 126. Detailsof the data are described below.

The image processing portion 40 processes image data input through theimage I/F portion 12 and outputs image signals to the optical modulatingdevice driving portion 46 under the control of the control portion 30.The processes performed by the image processing portion 40 are a processof determining a three-dimensional (3D) image and a plane (2D) image, aresolution converting process, a frame rate converting process, adistortion correction process, a digital zoom process, a color tonecorrection process, a brightness correction process, and the like. Theimage ting portion 40 executes a process designated by the controlportion 30, and performs a process by using a parameter input from thecontrol portion 30, if necessary. In addition, it is also possible tocombine and execute a plurality of processes among the processesdescribed above.

The image processing portion 40 is connected to the frame memory 44. Theimage processing portion 40 develops image data input from an imageinput I/F 12 on the frame memory 44, and executes the various processeswith respect to the developed image data. The image processing portion40 reads processed image data from the frame memory 44, generates imagesignals of RGB corresponding to the image data, and outputs thegenerated image signals to the optical modulating device driving portion46.

The optical modulating device driving portion 46 is connected to theliquid crystal panel of the optical modulating device 22. The opticalmodulating device driving portion 46 drives the liquid crystal panelbased on the image signals input from the image processing portion 40,and draws the image on the respective liquid crystal panels.

The operation detecting portion 17 is connected to a remote lightreceiving portion 18 and an operation panel 19 which function as inputdevices, and detects operations through the remote light receivingportion 18 and the operation panel 19.

The remote light receiving portion 18 receives an infrared signaltransmitted according to a button operation by a remote controller (notillustrated) used by the user of the projector 10 by the remote lightreceiving portion 18. The remote light receiving portion 18 decodes theinfrared signal received from the remote controller, generates operationdata indicating operation contents according to the remote controller,and outputs the operation data to the control portion 30.

The operation panel 19 is provided on the exterior housing of theprojector 10, and has various kinds of switches and indicator lamps. Theoperation detecting portion 17 appropriately turns on and off theindicator lamp of the operation panel 19 according to the operationstate and the setting state of the projector 10 according to the controlof the control portion 30. If the switch of the operation panel 19 isoperated, the operation data according to the operated switch is outputfrom the operation detecting portion 17 to the control portion 30.

An emitting device driving portion 48 is connected, to the lightemitting apparatus 60 through a connecting portion 49. The connectingportion 49 is, for example, a connector having a plurality of pins, andthe light emitting apparatus 60 is connected to the connecting portion49 through a cable 60 a. The emitting device driving portion. 48generates a pulse signal according to the control of the control portion30, and is output to the light emitting apparatus 60 through theconnecting portion 49. In addition, the emitting device driving portion48 supplies electric power to the light emitting apparatus 60 throughthe connecting portion 49.

The light emitting apparatus 60 accommodates the light source portion 61and optical components in a substantially box-shaped case as illustratedin FIG. 1. The light emitting apparatus 60 according to the presentembodiment includes a solid light source (not illustrated) thatgenerates infrared light to the light source portion 61. The infraredlight generated by the solid light source is diffused by a collimatinglens and a Powell lens, and forms a surface along the screen SC. Inaddition, the light source portion 61 includes a plurality of solidlight sources and may form a light layer so that the image projectionscope of the screen SC is covered, by respectively diffusing lightgenerated by the plurality of solid light sources. In addition, thelight emitting apparatus 60 may include an adjustment mechanism thatadjusts a distance and an angle between the light layer generated by thelight source portion 61 and the screen SC.

The light emitting apparatus 60 turns on the light source portion 61 bya pulse signal and electric power supplied from the emitting devicedriving portion 48. The timing at which the light source portion 61 isturned on and off is controlled by the emitting device driving portion48. The control portion 30 controls the emitting device driving portion48, and turns on the light source portion 61 in synchronization with thetiming at which an imaging portion 51 described below performscapturing.

The position detection portion 50 detects the operation of the screen.SC by the indicators 70 and 80. The position detection portion 50includes the imaging portion (imaging portion) 51, a transmittingportion (first transmitting portion) 52, a imaging control portion 53,captured image data processing portion 56, a frame memory 58, anindicator detecting portion 54, and a coordinate calculating portion 55.

The imaging portion 51 captures an image of the screen SC and theperipheral portion (detection area) thereof as a capturing target scopein order to detect the indication positions of the indicators 70 and 80.In addition, the imaging portion 51 has an imaging optical system, animaging element, an interface circuit, and the like, and captures theprojection direction of the projection optical system 23. The imagingoptical system of the imaging portion 51 is arranged towardsubstantially the same direction of the projection optical system 23,and has an angle of view that covers the scope in which the projectionoptical system 23 projects an image on the screen SC. In addition, theimaging element includes a CCD or a CMOS that receives light in aninfrared region and a visible light region. The imaging portion 51 mayinclude a filter for blocking a portion of light incident to the imagingelement, and, for example, may arrange a filter for mainly transmittinglight in the infrared region when the infrared light is received, beforethe imaging element. In addition, the interface circuit of the imagingportion 51 reads and outputs a detection value of the imaging element.

The imaging control portion 53 performs capturing by the imaging portion51 and generates the data of the captured image. If the imaging elementcaptures visible light, the image projected on the screen SC iscaptured. For example, the auto calibration image described belowcaptures visible light. In addition, when the imaging control portion 53can capture infrared image by the imaging portion 51, the infrared light(infrared signal) generated by the indicator 70 and the reflected lightreflected by the indicator 80 are taken in the captured image at thispoint.

The captured image data processing portion 56 develops the capturedimage data captured by the imaging portion 51 and obtained from theimaging control portion 53 to the frame memory 58. The captured imagedata processing portion 56 stores a mask image described below, andperforms a mask process by overlapping the mask image with the data ofthe captured image developed in the frame memory 58. The captured imagedata processing portion 56 outputs the data of the captured image afterthe mask process to the indicator detecting portion 54.

The indicator detecting portion 54 detects the indication positions ofthe indicators 70 and 80 by using concentration threshold valuesdifferent according to the position of the screen. SC based on the dataof the captured image captured by the imaging control portion 53. Theconcentration threshold value is set to be a value different accordingto a distance from the imaging portion 51 to the positions on the screenSC. Specifically, the concentration threshold value is set to be greateras the distance from the imaging portion 51 becomes closer. Details ofthe concentration threshold value and the process of detectingindication positions of the indicators 70 and 80 from the data of thecaptured image by using the concentration threshold value arehereinafter described with reference to FIGS. 15A and 15B.

The indicator detecting portion 54 detects at least one of an image ofthe infrared light generated by the indicator 70 and an image of thereflected light reflected on the indicator 80, from the data of thecaptured image when the imaging control portion 53 captures the infraredlight by the imaging portion 51. Additionally, the indicator detectingportion 54 may determine whether the detected image is an image of thelight generated by the indicator 70 or an image of the reflected lightof the indicator 80.

The coordinate calculating portion 55 calculates the coordinates of theindication positions of the indicators 70 and 80 according to the dataof the captured image based on the position detected by the indicatordetecting portion 54, and outputs the coordinates to the control portion30. The coordinate calculating portion 55 may calculate the coordinatesof the indication positions of the indicators 70 and 80 with respect tothe projection image projected by the projecting portion 20 and outputthe coordinates to the control portion 30. Additionally, the coordinatecalculating portion 55 may calculate the coordinates of the indicationpositions of the indicators 70 and 80 with respect to the image datawhich is drawn by the image processing portion 40 in the frame memory 44and the coordinates of the indication positions of the indicators 70 and80 with respect to the input image data of the image I/F portion 12.

The transmitting portion 52 transmits the infrared signal to theindicator 70 under the control of the indicator detecting portion 54.The transmitting portion 52 has a light source of an infrared LED or thelike, and turns on and off the light source under the control of theindicator detecting portion 54.

In addition, the indicator 70 includes a control portion 73, thetransmitting and receiving portion 74, the operating switch 75, and apower supply portion 76, and the elements are accommodated in the shaftportion 72 (FIG. 1). The control portion 73 is connected to thetransmitting and receiving portion 74 and the operating switch 75, anddetects the on/off state of the operating switch 75. The transmittingand receiving portion 74 includes a light source such as an infrared LEDand a light receiving element that receives the infrared light, turns onand off the light source under the control of the control portion 73,and outputs the light reception state of the light receiving element tothe control portion 73.

The power supply portion 76 has a battery or a secondary battery aspower supply, and supplies electric power to the control portion 73, thetransmitting and receiving portion 74, and the operating switch 75.

The indicator 70 may include a power supply switch that turns on and offthe power supply from the power supply portion 76.

Here, a method for specifying the indicator 70 from the data of thecaptured image of the imaging portion 51 by the communication betweenthe position detection portion 50 and the indicator 70 is described.

When the position indication operation is detected by the indicator 70,the control portion 30 transmits a signal for synchronization from thetransmitting portion 52 by controlling the indicator detecting portion54. That is, the indicator detecting portion 54 turns on the lightsource of the transmitting portion 52 in a predetermined cycle under thecontrol of the control portion 30. The infrared light periodicallygenerated by the transmitting portion 52 functions as a synchronizationsignal for synchronizing the position detection portion 50 and theindicator 70.

Meanwhile, after the supply of electric power from the power supplyportion 76 is started and predetermined initialization operation isperformed, the control portion 73 receives the infrared light generatedby the transmitting portion 52 of the projector 10 by the transmittingand receiving portion 74. If the infrared light periodically generatedby the transmitting portion 52 is received by the transmitting andreceiving portion 74, the control portion 73 turns on (emits) the lightsource of the transmitting and receiving portion 74 in the presetlighting pattern in synchronization with the timing of the infraredlight. The lighting pattern indicates data specific to the indicator 70,by associating the turning on and off of the light source with theON/OFF of the data. The control portion 73 turns on and off the lightsource according to the set turning-on time and the set turning-off timeof the pattern. The control portion 73 repeats the pattern while theelectric power is supplied from the power supply portion 76.

That is, the position detection portion 50 periodically transmits theinfrared signal for the synchronization to the indicator 70, and theindicator 70 transmits the preset infrared signal in synchronizationwith the infrared signal transmitted by the position detection portion50.

The imaging control portion 53 of the position detection portion 50control s the capturing timing by the imaging portion 51 insynchronization with the timing at which the indicator 70 turns onlight. The capturing timing is determined based on the timing at whichthe indicator detecting portion 54 turns on the transmitting portion 52.The indicator detecting portion 54 can specify the pattern at which theindicator 70 is turned on according to whether the image of the light ofthe indicator 70 is reflected in the data of the captured image of theimaging portion 51.

The pattern for turning on the indicator 70 can be a pattern specific toeach item of the indicators 70, or a pattern including a pattern commonto a plurality of the indicators 70, and a pattern specific to each itemof the indicators 70. In this case, when the images of the infraredlight generated by the plurality of indicators 70 are included in thedata of the captured image, the indicator detecting portion 54 candistinguish respective images as images of the different indicators 70.

In addition, the control portion 30 synchronizes the timing of turningon the light source portion 61 with the timing of capturing of theimaging portion 51 by controlling the emitting device driving portion48. If the light source portion 61 is turned on by pulses insynchronization with the capturing timing of the imaging portion 51,when the indicator 80 points on the screen SC, the reflected light ofthe indicator 80 is reflected on the captured image of the imagingportion 51. If the light source portion 61 is turned on at a patternthat is distinctive to the timing of turning on the indicator 70, theindicator detecting portion 54 can determine whether the image reflectedon the data of the captured image is the indicator 70 or the indicator80. For example, a case of turning on the light source portion 61 in apattern of “1010101010” (1 indicates turning on and 0 indicates turningoff) by turning on the indicator 70 in synchronization with the entirecapturing timing of the imaging portion 51 may be considered. In thiscase, the image captured when the light source portion 61 is not turnedon can be determined as an image captured by the indicator 70.

Additionally, the control portion 73 included in the indicator 70 mayswitch the pattern for turning on the transmitting and receiving portion74 according to the operation state of the operating switch 75.Therefore, the indicator detecting portion 54 can determine theoperation state of the indicator 70 based on the plurality of the dataof the captured image, that is, whether the tip portion 71 is pressed onthe screen SC.

An attitude sensor 47 is formed by an acceleration sensor, a gyrosensor, or the like, and output s a detection value to the controlportion 30. The attitude sensor 47 fixed to the main body of theprojector 10 in a manner so as to be capable of identifying theinstallation direction of the projector 10.

The projector 10 can be used in an installation state of performingprojection from a lower side of the screen SC, and in an installationstate of using a horizontal surface such as the upper surface of a deskas the screen SC in addition to the suspension installation of beingsuspended from the surface of a wall or a ceiling as illustrated inFIG. 1. There may be an installation state of the projector 10 which isnot suitable for the usage of the light emitting apparatus 60. Forexample, when the projection is performed on the screen SC from thelower side, the body of the user may block the emission light of thelight emitting apparatus 60. Therefore, the installation isinappropriate. The attitude sensor 47 is installed on the main body ofthe projector 10 so as to identify the plurality of installation statesassumed as the installation states of the projector 10. The attitudesensor 47 may be formed by using, for example, a dual axis gyro sensor,a single axis gyro sensor, or an acceleration sensor. The controlportion can automatically determine the installation state of theprojector 10 based on the output value of the attitude sensor 47. Whenthe control portion 30 is determined to be in installation state whichis inappropriate for the usage of the light emitting apparatus 60, forexample, the emitting device driving portion 48 stops an output of thepower supply voltage or the pulse signal.

The control portion 30 realizes functions of a projection controlportion 31, a detection control portion 32, an emission control portion33, and a calibration control portion 39 (mask image generating portion)by reading and executing the control program 111 recorded in the storageportion 110, and controls respective elements of the projector 10.

The projection control portion 31 acquires the operation contentsperformed by the user based on the operation data input from theoperation detecting portion 17. The projection control portion 31controls the image processing portion 40, the light source drivingportion 45, and the optical modulating device driving portion 46 underthe operation of the user, and causes the image to be projected on thescreen SC. The projection control portion 31 controls the imageprocessing portion 40, and executes the determination process of athree-dimensional (3D) image and a plane (2D) image as described above,a resolution converting process, a frame rate converting process, adistortion correction process, a digital zoom process, a color tonecorrection process, a brightness correction process, and the like. Inaddition, the projection control portion 31 controls the light sourcedriving portion 45 in combination with the process of the imageprocessing portion 40, and controls the light amount of the light sourceportion 21.

The detection control portion 32 controls the position detection portion50, detects the operation positions of the indicators 70 and 80, andacquires the coordinates of the operation positions. In addition, thedetection control portion 32 acquires data for identifying whether thedetected operation position is an operation position of the indicator 70or an operation position of the indicator 80, and data for indicating anoperation state of the operating switch 75 together with the coordinatesof the operation positions. The detection control portion 32 executesthe preset process based on the acquired coordinates and data. Forexample, the detection control portion 32 executes a process of causingthe image processing portion 40 to draw a diagram based on the acquiredcoordinates and superimposing and projecting the drawn diagram with aninput image input to the image I/F portion 12. In addition, thedetection control portion 32 may output the acquired coordinates to anexternal apparatus such as a PC connected to the I/F portion 11. In thiscase, the detection control portion 32 may convert the acquiredcoordinates into a data format identified as an input of a coordinateinput device in an operating system of an external apparatus connectedto the I/F portion 11 to output. For example, when a PC that operates inthe Windows (registered trademark) operating system is connected to theI/F portion 11, data processed as input data of a Human Interface Device(HID) in the operating system is output. In addition, the detectioncontrol portion 32 may output data for determining whether an operationposition is the operation position of the indicator 70 or the operationposition of the indicator 80, and data for indicating the operationstate of the operating switch together with the coordinate data.

In addition, the detection control portion 32 controls the positiondetection using the indicator 80. Specifically, the detection controlportion 32 determines whether the light emitting apparatus 60 can beused or not, based on the connection or the non-connection of the lightemitting apparatus 60. When the light emitting apparatus 60 cannot beused, the detection control portion 32 performs setting so that thelight emitting apparatus 60 cannot be used. Here, the detection controlportion 32 may report that the light emitting apparatus 60 cannot beused.

The emission control portion 33 executes or stops the output of thepower supply and the pulse signal to the light emitting apparatus 60connected to the connecting portion 49 by controlling the emittingdevice driving portion 48. When the light emitting apparatus 60 may notbe used or is not used, the emission control portion 33 stops the outputof the power supply and the pulse signal of the emitting device drivingportion 48 under the control of the detection control portion 32. Inaddition, when using the light emitting apparatus 60, the emissioncontrol portion 33 outputs the power supply and the pulse signal theemitting device driving portion 48.

The calibration control portion 39 detects the indication positions ofthe indicator 70 and the indicator 80, and executes a calibration forconverting the indication positions into the coordinates in the inputimage of the image I/F portion 12.

A process sequence of the control portion 30, especially, a processsequence of the calibration control portion 39 is described withreference to the flow chart of FIG. 3 and the accompanying drawings.

The calibration is executed as one of the initial settings when theprojector 10 is initially used. For example, the calibration is aprocess of associating the position in the image which is drawn in theframe memory 44 and projected by the projecting portion 20 and theposition on the data of the captured image captured by the imagingportion 51. The indication positions of the indicators 70 and 80detected by the position detection portion 50 from the data of thecaptured image are positions in the data of the captured image, and areindicated by, for example, the coordinates in the coordinate system setin the captured image. The user is aware of the projection imageprojected on the screen SC, and performs indication with the indicators70 and 80. Accordingly, the projector 10 is required to specify theindication position in the projection image on the screen SC. Thecoordinates of the positions detected with the data of the capturedimage can be converted into the coordinates on the projection image databy the calibration. The data that performs the association is set to bethe calibration data. The calibration data is data for associating thecoordinates on the data of the captured image output by the imagingcontrol portion 53 with the coordinates on the projection image.Specifically, the calibration data may be a table in which thecoordinates on the data of the captured image and the coordinates on theprojection image are associated one by one, and may be a function forconverting the coordinates on the data of the captured image into thecoordinates on the projection image.

The calibration control portion 39 may execute the calibrationcorresponding to the kinds of the indicators. That is, the calibrationcontrol portion 39 executes two kinds of calibrations: a calibrationrelating to the detection of the indication position of the indicator 70and a calibration relating to the detection of the indication positionof the indicator 80.

FIGS. 4A and 4B are explanatory diagrams illustrating a state ofdetecting the indication positions of the indicators 70 and 80, FIG. 4Aillustrates a state of detecting the indication position of theindicator 70, and FIG. 4B illustrates a state of detecting theindication position of the indicator 80.

In FIG. 4A, the capturing direction in which the imaging portion 51captures an image of the screen SC is indicated with a reference numeralPA. When the position detection of the indicator 70 is performed, thetransmitting and receiving portion 74 emits the infrared light from alight emitting position 70 a at the tip of the indicator 70. The lightemitting position 70 a is extremely close to a contacting point 70 b atwhich the indicator 70 is in contact with the screen SC. Therefore, whenan image of the light generated by the indicator 70 from the data of thecaptured image captured in the capturing direction PA is detected, theposition of the image may be assumed to be the position of thecontacting point 70 b.

Accordingly, when the indication position of the indicator 80 isdetected as illustrated in FIG. 4B, the reflected light obtained fromthe indicator 80 by reflecting detection light L that the light emittingapparatus 60 emits is detected. That is, the image of the reflectedlight of the detection light L is detected from the data of the capturedimage captured in the capturing direction PA. The emission direction ofthe detection light L is substantially parallel to the screen SC, andthe detection light L is separated from the screen SC by a predetermineddistance (hereinafter, referred to as a distance G1). The distance G1changes according to the installation position of the light emittingapparatus 60 with respect to the screen SC, but it is difficult to setthe distance G1 to be zero due to the structure. Therefore, the image ofthe reflected light reflected on the tip of the indicator 80 to areflection position 80 a separated from the screen SC by the distance G1is taken on the data of the captured image captured in the capturingdirection PA.

As illustrated in FIG. 4B, the reflection position 80 a is separated inan oblique direction with respect to the capturing direction PA.Therefore, the position of the image of the reflected light which istaken in the data of the captured image becomes the same position as theimage when a farther position is indicated by the indicator 70 in thecapturing direction PA. That is, the reflected light when the indicator80 is in contact with the screen SC at a contacting point 80 b and thelight when the indicator 70 is in contact with the screen SC at thecontacting point 70 b are taken at the same position in the data of thecaptured image of the imaging portion 51. Therefore, the contactingpoint 80 b pointed by the indicator 80 is detected as the contactingpoint 70 b separated from the imaging portion 51 in the capturingdirection PA to be deviated by a distance G2.

The deviation of the distance G2 is caused because the imaging portion51 obliquely performs capturing from the position separated from thescreen SC. For example, the positional relationship between thecapturing direction PA and the indicators 70 and 80 illustrated in FIGS.4A and 4B is not limited to the vertical direction, but is generated inthe same manner in the horizontal direction. According to the presentembodiment, since one imaging portion 51 provided on the main body ofthe projector 10 positioned over the screen SC illustrated in FIG. 1overlooks the screen SC and performs capturing, the deviation of thedistance G2 is generated in both the vertical and horizontal directions.

At this point, when the projector 10 detects the indication position ofthe indicator 80, after the indication position is detected in the samemanner as the indication position of the indicator 70 is detected, thedetected position is corrected.

Specifically, the calibration control portion 39 generates thecalibration data by performing calibration relating to the detection ofthe indication position of the indicator 70. If the calibration data isused, for example, as illustrated in FIG. 4A, when the light emittingposition 70 a is close to the contacting point 70 b with the screen SC,the indication position can be highly accurately detected.

Additionally, when the projector 10 detects the indication position ofthe indicator 80, the correction data for correcting coordinatescalculated by the calibration data is used. The correction data is theinitial correction data 125 and the manual correction data 126,specifically.

The correction data can be data for determining the distance G1 of FIG.4B. In this case, the correction data may be in a table format or mapdata in which each of the coordinates on the data of the captured imageor each of the coordinates on the projection image is associated withthe data indicating the length of the distance G1. In addition, thecorrection data may be in a table format in which a representative pointin the coordinates on the data of the captured image or in thecoordinates on the projection image is associated with the dataindicating the length of the distance G1. When a length of the distanceG1 of the coordinates deviated from the representative point is requiredto be calculated, a method of applying the distance G1 of therepresentative point close to correction target coordinates or a methodof calculating the distance G1 of the correction target coordinates fromthe distance G1 of the representative point by interpolation calculationcan be used.

In addition, for example, the correction data may data for shifting thecoordinates detected on the data of the captured image or thecoordinates on the projection image obtained based on the calibrationdata. Specifically, the correction data may be data for determining ashift amount of the coordinates or may be a function for correcting thecoordinates. In addition, the correction data may be data for realizingdifferent shift amounts for each of the coordinates on the data of thecaptured image or the coordinates on the projection image. In this case,the correction data may be a table in which shift amounts of thecoordinates are associated with the correction target coordinates. Thetable may be obtained by associating the shift amount with therepresentative point selected from the coordinates on the data of thecaptured image or the coordinates on the projection image. Whencoordinates other than the representative point is corrected, a methodof applying a shift amount of the representative point near thecorrection target coordinates or a method of calculating the shiftamount of the correction target coordinates from the shift amount of therepresentative point by the interpolation calculation can be used.

The calibration control portion 39 can execute the auto calibration andthe manual calibration as calibrations relating to the indicationposition of the indicator 70.

The auto calibration is a process of projecting an image for the autocalibration on the screen SC, capturing the image with the imagingportion 51, and generating calibration data by using the data of thecaptured image. The auto calibration is a process that can beautomatically executed by the projector 10, and does not require theoperation of the indicators 70 and 80 by the user. The auto calibrationis not limited to a case in which the user instructs the execution withthe remote controller or the operation panel 19, and may be executed atthe timing controlled by the control portion 30. For example, the autocalibration may be performed at the time of starting an operation rightafter the electric power of the projector 10 is turned on, or may beperformed during the normal operation described below. The autocalibration image 121 projected by the auto calibration is stored in thestorage portion 110 in advance.

FIG. 5 is an example of the auto calibration image 121. A plurality ofmarks (symbols) are arranged in the auto calibration image 121 at apredetermined interval. The mark in the calibration image is a diagramor a symbol that can be detected from the data of the captured image,and the shape or the size is not particularly limited.

FIG. 6 is a diagram illustrating an example of the data of the capturedimage obtained by capturing the auto calibration image 121 projected onthe screen SC by the imaging portion 51. When the projector 10 isinstalled in a suspending manner as illustrated in FIG. 1, the data ofthe captured image of the imaging portion 51 is captured from theobliquely upper side of the screen SC, so the image becomes distorted.FIG. 5 illustrates an example of the rectangular auto calibration image121 in which marks are lined up at even intervals, but an image having adistorted shape is taken in, the data of the captured image of FIG. 6,and the intervals of the lined-up marks inside the image are differentaccording to the positions of the marks.

The calibration control portion 39 operates the image processing portion40 and the projecting portion 20 based on the auto calibration image 121stored in the storage portion 110 by the function of the projectioncontrol portion 31, and projects the auto calibration image 121 on thescreen. SC. The calibration control portion 39 obtains the data of thecaptured image by controlling the position detection portion 50 andcausing the imaging portion 51 to capture an image. The data of thecaptured image is temporarily stored in a memory (not illustrated) fromthe imaging control portion 53, and is output to the control portion 30.The calibration control portion 39 detects the mark from the data of thecaptured image, and acquires the centroid positions of the respectivemarks as coordinate values of the marks. The calibration control portion39 associates the mark detected from the data of the captured image withthe projection image drawn in the frame memory 44, that is, the mark ofthe auto calibration image 121.

The calibration control portion 39 creates the auto calibration data 123in a table format or a function format by associating the coordinatevalues of the marks in the captured image and the coordinate values ofthe marks in the projection image. The coordinate values of the marks ofthe auto calibration image 121 in the projection image are stored inadvance in the storage portion 110 together with the auto calibrationimage 121, or are included in the auto calibration image 121 to bestored in the storage portion 110 in advance. When the auto calibrationdata 123 is already stored, the calibration control portion 3 a updatesthe auto calibration data 123.

FIG. 7 is a diagram illustrating an example of a calibration datamanaging table in which the calibration data is registered. Thecalibration data managing table illustrated in FIG. 7 is a table inwhich identification numbers of the marks arranged on the autocalibration image 121 and the central coordinates of the respectivemarks on the auto calibration image 121 are associated with each otherand recorded. The calibration data managing table is stored in thestorage portion 110 in association with the auto calibration image 121.The central coordinates on the frame memory 44 of the respective marksare recorded in the calibration managing table in association with theidentification numbers of the respective marks. Further, coordinatevalues (the maximum value and the minimum value in the X-coordinates andthe Y-coordinates) in the scope in which the respective marks arepositioned may be stored in switch of the central coordinates, as theposition coordinates of the respective marks. Based on the coordinatesregistered in the calibration data managing table and the coordinatesdetected from the data of the captured image by the position detectionportion 50, the coordinates on the data of the captured image and thecoordinates on the frame memory 44 are associated with each other, andthe auto calibration data 123 is generated.

The calibration control portion 39 executes the calibration one time tocreate or update the auto calibration data 123. Otherwise, thecalibration control portion 39 substitutes the auto calibration image121, and performs the association of coordinates with a plurality ofimages. Then, the calibration control portion 39 may combine associationresults obtained by the plurality of auto calibrations, and may createthe highly accurate auto calibration data 123.

According to the present embodiment, the plurality of auto calibrationimages 121 are stored in the storage portion 110. The calibrationcontrol portion 39 selects one auto calibration image 121 from the autocalibration images 121 stored in the storage portion 110. It is possibleto enhance the detection accuracy of the indication coordinates by theindicators 70 and 80 by preparing the plurality of auto calibrationimage 121 and performing the auto calibration a plurality of times. Forexample, images in which positions of marks in the first and second autocalibrations are different are used. In order to enhance the detectionaccuracy of the indication coordinates by the indicators 70 and 80, acertain size (dimension) is required in the mark. Therefore, it ispossible to enhance the detection accuracy of the indication coordinatesby the indicators 70 and 80 by using an image in which the autocalibration is performed twice, and further the mark positions on theauto calibration image 121 are different. In addition, the calibrationcontrol portion 39 may use the plurality of auto calibration images 121in one auto calibration. Further, FIG. 5 illustrates a diagramillustrating an example in which an X-shaped mark is used, but the shapeof the mark, the size of the mark, the number of marks included in theauto calibration image 121, and the arrangement of the marks are notlimited, either.

The manual calibration is a process of projecting an image for themanual calibration on the screen SC, detecting the operation of theindicator 70 corresponding to the projected image, and generating themanual calibration data.

FIG. 8 is a diagram illustrating an example of the manual calibrationimage 122. The manual calibration image 122 includes a mark showing theindication position in order to cause the user to perform indicationwith the indicator 70. In the manual calibration image 122 of FIG. 8, aplurality of indication marks (o) are arranged, and the user indicatesthe positions of the marks with the indicator 70.

The plurality of marks are included in the manual calibration image 122,but the marks are projected on the screen SC one by one. Therefore, themanual calibration image 122 is specifically formed with the combinationof the plurality of images having the different number of marks.

Every time marks are displayed on the screen SC, the user indicates anewly displayed mark with the indicator 70. The calibration controlportion 39 detects the indication position every time the user performsthe operation. Then, the calibration control portion 39 associates theindication positions detected in the captured image and the projectionimages drawn in the frame memory 44, that is, the marks of the manualcalibration image 122. The calibration control portion 39 creates themanual calibration data 124 by associating the coordinate values of theindication positions detected with the data of the captured image andthe coordinate values of the marks on the projection image.

The manual calibration data 124 may be formed in the same data formatwith the auto calibration data 123, but can be set to be the correctiondata for correcting the auto calibration data 123. The auto calibrationdata 123 is data for converting the coordinates on the captured imageinto the coordinates on the projection image. On the contrary, themanual calibration data 124 is the data for further correctingcoordinates after the conversion by using the auto calibration data 123.

When the calibration relating to the detection of the indicationpositions of the indicator 70 is performed, the calibration controlportion 39 can execute the auto calibration or the manual calibration.When the storage portion 110 stores the auto calibration data 123generated in the past, the auto calibration and the manual calibrationcan be selectively executed. Here, when the auto calibration isexecuted, the calibration control portion 39 updates the autocalibration data 123 of the storage portion 110. In addition, when themanual calibration is executed, the manual calibration data 124 isgenerated or updated. In addition, when the auto calibration data 123 isnot stored in the storage portion 110, is required to execute the autocalibration. It is because the manual calibration data 124 may not beused when the auto calibration data 123 is not stored.

The calibration control portion 39 can execute the calibration relatingto the detection of the indication position of the indicator 80 in thesame manner as the manual calibration of the indicator 70. In this case,the calibration control portion 39 generates the manual correction data126. The manual correction data 126 is used when the indication positionof the indicator 80 is detected.

The manual correction data 126 is the data for correcting thecoordinates detected as the indication position of the indicator 70 intothe coordinates of the indication position of the indicator 80 asdescribed above with reference to FIG. 4B. The calibration controlportion 39 selects the initial correction data 125 when the manualcalibration is not performed in the detection of the indication positionof the indicator 80. The initial correction data 125 is correction datain which the distance G1 of FIG. 4B is set to be the initial value andstored in the storage portion 110 in advance. The distance G1 betweenthe screen SC and the detection light L is adjusted to be, for example,1 mm to 10 mm at the time of installing the light emitting apparatus 60,and actually changes in the plane of the screen SC. The initialcorrection data 125 is the correction data in the case in which theinitial value of the distance G1 is assumed to be 5 mm, and if theinitial correction data 125 is used, the indication position of theindicator 80 can be detected without using manual calibration. If themanual correction data 126 created in the manual calibration is used,the indication position of the indicator 80 can be more accuratelydetected by performing the correction in which the difference in theplane of the distance G1 is reflected.

That is, with respect to the position detection of the positiondetection portion 50, when the detection control portion 32 detects theindication position of the indicator 70, the coordinates of theindication position is calculated by using the auto calibration data 123or the manual calibration data 124. When the indication position of theindicator 80 is detected, the detection control portion 32 corrects theinitial correction data 125 or the manual correction data 126 in theprocess of calculating coordinates by using the auto calibration data123 or the manual calibration data 124. In other words, the initialcorrection data 125 and the manual correction data 126 are data of thedifference for obtaining the indication position of the indicator 80from the indication position of the indicator 70.

In the flow chart of FIG. 3, the selection of whether to execute theauto calibration or to execute the manual calibration is performed bythe user (Step S1). The calibration control portion 39 detects theoperation of the remote controller or the operation panel 19 (Step S2),the process proceeds to Step S2 when the auto calibration is selected,and the process proceeds to Step S7 when the manual calibration isselected. Further, as described above, when the auto calibration data123 is not stored in the storage portion 110, a menu screen in whichonly the auto calibration can be selected can be projected in Step S1.

In Step S2, the calibration control portion 39 selects the autocalibration image 121. Since the plurality of auto calibration images121 are stored in the storage portion 110, the calibration controlportion 39 selects one auto calibration image 121 among the autocalibration images 121 stored in the storage portion 110.

Subsequently, the calibration control portion 39 projects the selectedauto calibration image 121 on the screen. SC by the projecting portion20 (Step S3). When the auto calibration image 121 is projected on thescreen SC, the user may adjust the display size and the display positionby the operation of the remote controller or the operation panel 19 sothat the auto calibration image 121 is settled in the display area ofthe screen SC.

The calibration control portion 39 causes the imaging portion 51 toperform capturing by controlling the position detection portion 50 (StepS4), and creates the auto calibration data 123 based on the obtaineddata of the captured image by obtaining the data of the captured imageof the imaging portion 51 (Step S5).

The calibration control portion 39 executes a background image creatingprocess (Step S6), and the process proceeds to Step S15.

FIG. 9 is a flow chart illustrating details of the background imagecreating process.

The calibration control portion 39 creates the mask image (Step S111).The mask image is the image for cutting the image data of the portioncorresponding to the display area of the screen SC from the data of thecaptured image captured by the imaging portion 51. FIG. 10 is a diagramillustrating an example of the mask image.

A method of creating the mask image is described with reference to FIG.11. FIG. 11 is a diagram illustrating an example of the data of thecaptured image. In FIG. 11, a lower left portion of the data of thecaptured image is set to be the origin so that the vertical direction isset to be the X axis direction and the horizontal direction is set to bethe Y axis direction.

The calibration control portion 39 determines the scope in which thescreen SC is taken, from the data of the captured image obtained bycapturing the projection image of the screen SC.

In the projector 10, already in Step S3, the projection image isadjusted by the user so as to be settled in the projection area of thescreen SC. In addition, the calibration control portion 39 obtains thedata showing which of the marks included in the auto calibration image121 are the mark columns positioned on the outermost sides in upper,lower, left, and right directions. The data is stored in the storageportion 110 in association with, for example, the auto calibration image121.

In the example illustrated in FIG. 11, the mark column positioned on theoutermost side on the left side of the auto calibration image 121 is amark column T. The calibration control portion 39 obtains the centralcoordinates of the respective marks included in the mark column T fromthe calibration data managing table illustrated in FIG. 7. Thecalibration control portion 39 determines the left end of the screen SCby adding a specified value that becomes the margin in the obtainedcentral coordinates of the respective marks. Since the mark column T isthe mark column positioned on the outermost side on the left side of theauto calibration image 121, the specified value is subtracted from theY-coordinate value of the respective marks to obtain the coordinatevalue on the left end of the screen SC. For example, in the case of amark T3 (X3, Y3) of the mark column T illustrated in FIG. 11, thecoordinates T3′ (X3, Y3-α) obtained by subtracting a specified value αfrom a Y-coordinate value Y3 becomes the left end of the screen SC inT3. The calibration control portion 39 obtains coordinate values of theend portions in the upper, lower, left, and right directions of thescreen SC. Further, with respect to the area in which the mark does notexist, the coordinate values of the end portions may be obtained by thesupplementary process. The calibration control portion 39 stores theobtained coordinate values in the upper, lower, left, and rightdirections in the storage portion 110. Next, the calibration controlportion 39 creates the mask image by using the obtained data in thescope of the screen SC. The calibration control portion 39 generates themask image which sets a pixel value to be 0 in the area outside thescope of the screen SC. The calibration control portion 39 sends thegenerated mask image to the captured image data processing portion 56 ofthe position detection portion 50.

Next, the calibration control portion 39 causes the imaging portion 51to capture the capturing scope by turning off the light source portion61 of the light emitting apparatus 60 (Step S112). When the capturing isperformed by the imaging portion 51, the calibration control portion 39causes the projecting portion 20 to project, for example, a messageimage that draws an attention not to operate the indicators 70 and 80 sothat the indicators 70 and 80 or the user is not captured. The data ofthe captured image captured in Step S112 while the light source portion61 of the light emitting apparatus 60 is turned off is called the firstbackground image data. FIG. 12 is a diagram illustrating an example ofthe first background image data, in the first background image dataillustrated in FIG. 12, the screen SC or the reflected light which isunintentionally taken in the screen SC is stored. The calibrationcontrol portion 39 stores the first background image data in the storageportion 110.

Next, the calibration control portion 39 causes the imaging portion 51to capture the capturing scope by turning on the light source portion 61of the light emitting apparatus (Step S113). When performing thecapturing, the calibration control portion 39, for example, causes themessage image to be projected on the projecting portion 20 so that theindicators 70 and 80 or the user is not captured. The data of thecaptured image captured in Step S113 while the light source portion 61of the light emitting apparatus 60 is turned on is called the secondbackground image data. FIG. 13 is a diagram illustrating an example ofthe second background image data. A pen tray that reflects the light ofthe light source portion 61 is taken in the second background image dataillustrated in FIG. 13, in addition to the screen SC and the reflectedlight reflected on the screen Sc by the detection light of the lightemitting apparatus 60. The calibration control portion 39 stores thesecond background image data in the storage portion 110.

Next, the calibration control portion 39 causes the imaging portion 51to capture the capturing scope by turning on the light source portion 61of the light emitting apparatus (Step S113). When performing thecapturing, the calibration control portion 39, for example, causes themessage image to be projected on the projecting portion 20 so that theindicators 70 and 80 or the user is not captured. The data of thecaptured image captured in Step S113 while the light source portion 61of the light emitting apparatus 60 is turned on is called the secondbackground image data. FIG. 13 is a diagram illustrating an example ofthe second background image data. A pen tray that reflects the light ofthe light source portion 61 is taken in the second background image dataillustrated in FIG. 13, in addition to the screen SC and the reflectedlight reflected on the screen. SC by the detection light of the lightemitting apparatus 60. The calibration control portion 39 stores thesecond background image data in the storage portion 110.

When the first background image data and the second background imagedata are captured, the calibration control portion 39 subtracts thefirst background image data from the second background image data, andgenerates differential image data (Step S114). Hereinafter, thedifferential image data is called light source noise data. Thecalibration control portion 39 stores the generated light source noisedata in the storage portion 110. The first background image data and thesecond background image data may be captured during a normal operationdescribed below.

Meanwhile, when the manual calibration is selected, the calibrationcontrol portion 39 proceeds to Step S7.

In Step S7, the background image creating process of Step S6 describedabove is executed. In Step S111 of FIG. 9, the mask image is created byprojecting the auto calibration image 121 on the screen SC, but the sameprocess is performed in Step 7.

After the mask image is created, the calibration control portion 39selects the manual calibration image 122 (Step S8), and projects theselected manual calibration image 122 on the screen SC by the projectingportion 20 (Step S9). When the manual calibration image 122 is projectedon the screen SC, the user may adjust the display size and the displayposition so that the manual calibration image 122 is settled in thedisplay area of the screen SC.

Here, an operation of using the indicator 70 is performed by the user(Step S10). As illustrated in FIG. 8, the predetermined marks arearranged in the manual calibration image 122. If the manual calibrationimage 122 is displayed on the screen SC, the user points to the marksprojected on the screen SC one by one by using the indicator 70. Thetransmitting portion 52 of the projector 10 periodically transmitsinfrared signals for synchronization. The indicator 70 turns on theinfrared light in synchronization with the infrared signal. Thecalibration control portion 39 causes the imaging portion 51 to capturethe capturing scope in synchronization with the light emission timing ofthe indicator 70. Accordingly, the data of the captured image(hereinafter, referred to as “first position detection image data”) inwhich the indicator 70 points the marks is captured. The calibrationcontrol portion 39 executes an indication position detecting process fordetecting the indication position of the indicator 70 by obtaining thedata of the captured image (Step S11).

Details of Step S11 are described with respect to the flow chartillustrated in FIG. 14. The first background image data is an image ofthe screen SC and the circumference thereof which is captured so thatthe indicator 70 and the user are not reflected by turning off the lightsource portion 61 of the light emitting apparatus 60. The disturbancecaused by the external light entering from a window, the light of theillumination such as a fluorescent light, and the reflected light whichis an external light or the light of the illumination reflected to thescreen SC are recorded in the first background mage data. These arecalled background noises.

The captured image data processing portion 56 obtains the data of thefirst position detection image captured by the imaging portion 51. Thecaptured image data processing portion 56 develops the obtained firstposition detection image data to the frame memory 58. The captured imagedata processing portion 56 performs the mask process by overlapping themask image in the frame memory 58 in which the first position detectionimage data is developed (Step S121). Further, hereinafter, the firstposition detection image data in the area corresponding to the screen SCwhich is cut in the mask process called cut image data. The capturedimage data processing portion 56 transmits the cut image data cut in themask process to the indicator detecting portion 54. The indicatordetecting portion 54 generates the differential image data in which thebackground noise is removed by subtracting the first background imagedata from the cut image data obtained from the captured image dataprocessing portion 56 (Step S122). Next, the indicator detecting portion54 binarizes differential image data using the concentration thresholdvalue (Step S123). That is, the indicator detecting portion 54 detectsthe pixels in which the pixel value is equal to or greater than theconcentration threshold value by comparing the pixel value of thedifferential image data and the concentration threshold value. Anexample of the concentration threshold value is illustrated in FIGS. 15Aand 15B. FIG. 15A is a diagram illustrating the concentration thresholdvalue which is set in combination with the mask image illustrated inFIG. 10, and FIG. 15B is a diagram illustrating concentration thresholdvalues in points A to D illustrated in FIG. 15A.

The concentration threshold value according to the present embodiment isupdated according to the distance from the imaging portion 51 in thedata of the captured image captured by the imaging portion 51, thebrightness of the captured image is lower as the distance from theimaging portion 51 to the subject is longer, and the brightness of thecaptured image is higher as the distance from the imaging portion 51 tothe subject is shorter. Therefore, in the position detection portion 50,the concentration threshold value in the scope in which the distancefrom the imaging portion 51 is short is set to be great, and theconcentration threshold value in the scope in which the distance fromthe imaging portion 51 is long is set to be small. In this manner, sincethe concentration threshold value is set to be obliquely installed, theinfrared light of the indicator 70 and the other images in the capturedimage are easily discriminated. In the example illustrated in FIG. 15B,the concentration threshold value is set to be greatest at the point Dat which the distance from the imaging portion 51 is closest, and theconcentration threshold value is set to be smallest at the point A atwhich the distance from the imaging portion 51 is farthest.

If a pixel of which the pixel value detected by binarization is equal toor greater than the concentration threshold value is detected, theindicator detecting portion 54 divides pixels into blocks for each lumpof detected pixels, and calculates centroid coordinates of the blocks ofwhich the areas are in a certain scope (Step S124). The centroidcoordinates refer to the positional central coordinates of the block.The calculation of the centroid coordinates is performed, for example,by respectively adding horizontal axis X components and vertical axis Ycomponents of the coordinates that are allocated to the blocks andobtaining the averages thereof. The position detection portion 50transmits the calculated centroid coordinates to the calibration controlportion 39. The calibration control portion 39 determines the centroidcoordinates obtained from the indicator detecting portion 54 to be theindication coordinates on the data of the captured image.

Further, in the example illustrated in FIG. 2, an example in which theposition detection portion 50 includes the frame memory 58 is described.In the simple structure in which the position detection portion 50 doesnot include the frame memory 58, the captured image data processingportion 56 may perform the mask process by outputting only the firstposition detection image data in the screen SC area among the firstposition detection image data to the indicator detecting portion 54.Specifically, the captured image data processing portion 56 calculatesthe coordinate values of the area corresponding to the screen SC on thedata of the captured image from the mask image obtained from thecalibration control portion 39. Then, if the first position detectionimage data is obtained from the imaging control portion 53, the capturedimage data processing portion 56 outputs only the first positiondetection image data of the area corresponding to the screen SC to theindicator detecting portion 54 based on the calculated coordinatevalues.

Returning to FIG. 3, the calibration control portion 39 associates theindication coordinates on the data of the captured image and thecoordinates on the auto calibration image 121 of the corresponding mark,and causes the storage portion 110 to store the associated coordinates(Step S12).

The calibration control portion 39 determines whether the indicationpositions with respect to the marks of all the manual calibration images122 are detected (Step S13), and returns to Step S9 when there is anunprocessed mark. In addition, when the indication position of all themarks are detected, the calibration control portion 39 creates themanual calibration data 124 based on the coordinate indication positionstemporarily stored in Step S12 and the positions of the marks (StepS14). Here, the created manual calibration data 124 is stored in thestorage portion 110. Thereafter, the calibration control portion 39proceeds to Step S15.

In Step S15, the calibration control portion 39 causes the projectingportion 20 to project the user interface for selecting whether themanual calibration related to the detection of the indication positionof the indicator 80 is executed, and causes the user to perform aselection input.

The calibration control portion 39 detects the operation of the remotecontroller or the operation panel 19, and determines whether the manualcalibration is executed (Step S16).

When the manual calibration is not executed (No in Step S16), thecalibration control portion 39 selects the initial correction data 125(Step S17) and proceeds to the normal operation (Step S18).

The normal operation projects the image to the screen SC based on theinput image input to the image 11F portion 12, specifies the indicationpositions indicated by the indicators 70 and 80, and operates theprocesses corresponding to the indication content.

When the manual calibration relating to the operation of the indicator80 is performed (Yes in Step S16), the calibration control portion 39selects the manual calibration image 122 (Step S19).

Subsequently, the calibration control portion 39 projects the selectedmanual calibration image 122 by the projecting portion 20 to the screenSC (Step S20). Here, an operation using the indicator 80 is performed bythe user (Step S21), and the calibration control portion 39 executes theindication position detecting process for detecting the indicationposition of the indicator 80 (Step S22). The indication positiondetecting process of Step S22 is a process performed in the same manneras the indication position detecting process of Step S11 describedabove, and executed as in FIG. 14.

In the indication position detecting process of Step S22, the positiondetection portion 50 (the indicator detecting portion 54) detects theindication coordinates pointed by a finger 80 a by using the secondposition detection image data, the mask image, the first backgroundimage data, and the second background image data. Further, the secondbackground image data is an image of the screen SC and thecircumferences thereof which are captured while the light source portion61 of the light emitting apparatus 60 is turned on. Therefore, inaddition to the background noise recorded in the first background imagedata, the light generated from the light source portion 61 of the lightemitting apparatus 60 and the reflected light thereof are recorded inthe second background image data. The noise caused by the lightgenerated by the light source portion 61 is called the source noise. InStep S8, the calibration control portion 39 generates the light sourcenoise data by subtracting the first background image data from thesecond background image data, and stores the light source noise data inthe storage portion 110. FIG. 16 is a diagram illustrating an example ofthe light source noise data.

The position detection portion 50 generates the differential image datain which the background noise and the light source noise are removed bysubtracting the first background image data and the light source noisedata from the second position detection image data. Since the processafter the differential image data is generated is the same as theprocess illustrated in FIG. 14, the description thereof is omitted. Theposition detection portion 50 transmits the calculated centroidcoordinates to the calibration control portion 39. The calibrationcontrol portion 39 determines the centroid coordinates obtained from theposition detection portion 50 to be the indication coordinates on thedata of the captured image. Then, the calibration control portion 39associates the indication coordinates on the data of the captured imageand the mark coordinate values of the corresponding marks on the manualcalibration image 122, and stores the associated values in the storageportion 110 (Step S23).

The calibration control portion 39 determines whether the indicationpositions with respect to all the marks of the manual calibration image122 are detected (Step S24), and returns to Step S20 if there is anunprocessed mark. In addition, if the indication positions of all themarks are detected, the calibration control portion 39 creates themanual correction data 126 based on the coordinates of the indicationpositions and the positions of the marks which are stored in Step S23(Step S25). Here, the created manual correction data 126 is stored inthe storage portion 110. Thereafter, the calibration control portion 39proceeds to Step S18, and starts the normal operation.

Further, the calibration control portion 39 may generate the manualcalibration data 124 including data in the same manner as the autocalibration data 123 by the manual calibration of the indicator 70. Inthis case, the calibration control portion 39 generates the manualcalibration data 124 which is the same as the auto calibration data 123by the processes in Steps S8 to S14 of FIG. 3. In addition, the autocalibration data 123 and the manual calibration data 124 may be set tobe the same data. In this case, the auto calibration data 123 generatedbefore is overwritten by the data generated in Step S14.

In this configuration, if the calibration control portion 39 executesany one of the auto calibration or the manual calibration, it ispossible to obtain the coordinates of the indication position of theindicator 70. Accordingly, in the operation of FIG. 3, when the autocalibration data 123 is not stored, it is possible to select the manualcalibration in Step S1.

Next, the light emission timings of the projector 10 (the transmittingportion 52) the indicator 70, and the light emitting apparatus 60 (thelight source portion 61) in the normal operation are described withreference to the sequence diagram illustrated in FIG. 17.

In the present sequence, the projector 10 becomes the master apparatus,and the light emission timing is reported to the indicator 70 and thelight emitting apparatus 60. The light source portion 61 of the lightemitting apparatus 60 and the indicator 70 emit light according to thetiming which is reported from the projector 10. In addition, four phasesfrom the first phase to the fourth phase are included in the presentsequence, and are repeated in the sequence from the first phase to thefourth phase. When the fourth phase ends, the process returns to thefirst phase, and the four phases repeat again from the first phase.Accordingly, the projector 10 reports the light emission timing to theindicator 70, and can perform the capturing in synchronization with thelight emission timing of the indicator 70 or the light emittingapparatus 60.

The first phase is the synchronization phase. In the first phase, thelight source of the transmitting portion 52 of the projector 10 isturned on, and the infrared signal for the synchronization istransmitted to the indicator 70. The indicator 70 can recognize thestart timing of the first phase by receiving the infrared signal for thesynchronization. Further, since the respective times of the first tofourth phases are set at the same time, the indicator 70 can recognizethe start timings of the second to fourth phases by recognizing thestart timing of the first phase.

The second phase is the position detection phase, and the light sourceportion 61 of the light emitting apparatus 60 and the indicator 70 areturned on. The projector 10 captures the capturing scope with theimaging portion 51 according to the lighting timings of the light sourceportion 61 and the indicator 70. Accordingly, when the indicator 80points to the screen SC, the reflected light of the indicator 80 istaken on the data of the captured image of the imaging portion 51. Inaddition, the light by the indicator 70 is taken in the data of thecaptured image of the imaging portion 51.

The third phase is the phase provided in order to discriminate theindication positions of the indicator 70 and the indicator 80 based onthe light emission timings of the indicator 70 and the light emittingapparatus 60. The third phase is the indicator determination phase, andthe indicator 70 is turned on in the specific lighting pattern set inthe indicator 70, and the light source portion 61 is not turned on.Therefore, the light from the indicator 70 is taken in the data of thecaptured image of the imaging portion 51. Among bright spots captured inthe second phase, it is possible to detect a position of a bright spottaken in the data of the captured image captured in the third phase inwhich the light emitting apparatus 60 is turned on as the indicationpositions of the indicator 70. That is, among the indication coordinatesdetected from the data of the captured image captured in the second andfourth phases, the indication coordinates close to the indicationcoordinates detected from the data of the captured image captured in thethird phase can be determined as the indication coordinates of theindicator 70.

In addition, an ID for identifying the indicator 70 is set in theindicator 70, and the indicator 70 in the third phase is turned onaccording to the set ID. When the plurality of indicators 70 are used,IDs are set for each of the indicators 70, and the respective indicators70 are turned on according to the set IDs. For example, “1000” may beallocated as an ID of the indicator 70 to set the indicator 70 to beturned on at “1”, and to set the indicator 70 to be turned off at “0”.In this case, the indicator 70 is turned on in the third phase duringthe first time, and is turned off in the third phase during the secondto fourth times. Accordingly, even if the indication operation isperformed with the plurality of indicators 70, the projector 10 candetect the indication position of the respective indicators 70.

In addition, the fourth phase is the position detection phase which isthe same as the second phase. The imaging portion 51 performs capturingwhile the light source portion 61 of the light emitting apparatus 60 andthe indicator 70 are turned on. Further, the projector 10 may update thefirst and second background image data by capturing the capturing scopeby the imaging portion 51, for example, in the first phase, the secondphase, and the fourth phase. By updating the first and second backgrounddata even during the normal operation, the detection accuracy of theindication coordinates by the indicators 70 and 80 can be enhanced. Forexample, in the first phase, after the infrared signal forsynchronization is transmitted, the projector 10 captures the capturingscope by the imaging portion 51. Since the data of the captured imagecaptured in the first phase is the image data in which the indicator 70and the light source portion 61 of the light emitting apparatus 60 arenot turned on, the data of the captured image can be used as the firstbackground image data. In addition, in at least one of the second andfourth phases, after the lighting of the indicator 70 ends, theprojector 10 captures the capturing scope by the imaging portion 51while the light source portion 61 of the light emitting apparatus 60 isturned on. The data of the captured image is the image data in which theindicator 70 is turned off and the light source portion 61 of the lightemitting apparatus 60 is turned on. Therefore, the data of the capturedimage can be used as the second background image data.

As described above, the projection system 1 according to the presentembodiment includes the light emitting apparatus 60 that emits detectionlight to the detection area for detecting indication positions of theindicators 70 and 80, and the projector 10 that detects the indicationpositions of the indicators 70 and 80 in the detection area. Theprojector 10 includes the imaging portion 51 and the position detectionportion 50. The imaging portion 51 captures the detection area. Theposition detection portion 50 detects at least one of an image of thelight generated by the indicator 70 and the image of the detection lightreflected by the indicator 80 from the data of the captured image. Then,the position detection portion 50 discriminates and detects theindication positions of the indicator 70 and the indicator 80 based onthe light emission timings between the indicator 70 and the lightemitting apparatus 60. Therefore, even if the invention has a simpleconfiguration, it is possible to accurately detect the indicationpositions of the different kinds of indicators by using the data of thecaptured image.

In addition, the position detection portion 50 detects the position of abright spot taken in the data of the captured image captured after thelight emitting apparatus 60 is turned off, as the indication position ofthe indicator 70. Accordingly, it is possible to easily discriminate theindicator 70 and the indicator 80, and it is possible to accuratelydetect the indication positions of the different kinds of the indicators70 and 80.

In addition, the position detection portion 50 determines the light thatthe plurality of indicators 70 generate according to the identificationinformation allocated for each of the indicators 70 based on the data ofthe captured image of the imaging portion 51, and discriminates anddetects the indication positions of the plurality of indicators 70.Accordingly, even if the plurality of indicators 70 are provided, it ispossible to discriminate the respective indicators 70 and detectindication positions of the respective indicators 70.

In addition, the projector 10 includes the transmitting portion 52 thattransmits the infrared signal for synchronization to report the lightingtiming of the indicators 70 and the emitting device driving portion 48that transmits a signal for informing the timing for emitting thedetection light to the light emitting apparatus 60, to the lightemitting apparatus 60. Therefore, the projector 10 can synchronizelighting timing of the indicator 70 and the light emitting apparatus 60,and capture the detection area by the imaging portion 51. Accordingly,it is possible to detect the indication positions of the indicator 70and the indicator 80.

Further, the embodiments and the modifications described above aremerely specific examples to which the invention is applied, and thespecific embodiments disclosed are not intended to limit the invention,and the invention may be applied according to another aspect. Accordingto the embodiments above, for example, the indicator is not limited tothe pen-type indicator 70 or the indicator 80 which is the finger of theuser, and a laser pointer, an indication rod, or the like may be used,and the shape and the size thereof are not limited.

In addition, according to the present embodiment and the modification,the light emitting apparatus 66 is configured as a separate body fromthe main body of the projector 10, and is connected to the projector 10through the cable 60 a, but the invention is not limited to this. Forexample, the light emitting apparatus 60 may be mounted on the main bodyof the projector 10 in an integrated manner, or may be embedded in themain body of the projector 10. In addition, the light emitting apparatus60 may receive power supply from the outside, and connected to theemitting device driving portion 48 through a wireless communicationcircuit.

In addition, according to the present embodiment, the position detectionportion 50 specifies the position of the indicator 70 by capturing thescreen SC by the imaging portion 51, but the invention is not limited tothis. For example, the imaging portion 51 is not limited to be providedon the main body of the projector 10 and to capture the projectiondirection of the projection optical system 23. The imaging portion 51may be arranged as a separate body from the main body of the projector10, and the imaging portion 51 may perform capturing from the sidedirection of the screen SC or in front of the screen SC. Additionally,the plurality of imaging portions 51 are arranged, and the detectioncontrol portion 32 may detect the positions of the indicators 70 and 80based on the data of the captured image of the plurality of imagingportions 51.

In addition, according to the embodiments described above, with respectto the indicator 70 from the projector 10, a configuration oftransmitting a signal for the synchronization to the indicator by usingthe infrared signal generated by the transmitting portion 52 isdescribed, but the signal for the synchronization is not limited to theinfrared signal. For example, the signal for the synchronization may betransmitted by radio wave communication or ultrasonic radio wavewireless communication. The configuration may be realized by providing atransmitting portion for transmitting a signal by radio wavecommunication or ultrasonic radio wave wireless communication to theprojector 10, and a receiving portion for receiving a signal in the samemanner to the indicator 70.

In addition, according to the embodiment described above, aconfiguration of using three transparent liquid crystal panelscorresponding to the respective colors of RGB described as the opticalmodulating device 22 for modulating the light generated by the lightsource, but the invention is not limited to this. For example, threereflective liquid crystal panels may be used, or a method of combiningone liquid crystal panel and a color foil may be used. Otherwise, amethod of using three sheets of digital mirror devices (DMD) or a DMDmethod of combining one digital mirror device and a color foil may beused. When a liquid crystal panel of one sheet only or DMD is used asthe optical modulating device, a member corresponding to the synthesisoptical system such as the cross dichroic prism is not required.Further, in addition to the liquid crystal panel and the DMD, if adevice is an optical modulating device that can modulate the lightgenerated by the light source, the device can be employed without aproblem.

According to the embodiment, it is described that the user performs theindication operation by the indicators 70 and 80 with respect to thescreen SC (a projection surface or a display surface) to which the frontprojection-type projector 10 projects (displays) an image, but the usermay perform the indication operation to a display screen (displaysurface) on which a display apparatus (display portion) other than theprojector 10 displays an image. In this case, the light emittingapparatus 60 or the imaging portion 51 may be configured to beintegrated with the display apparatus, or may be configured to be aseparate body from the display apparatus. As the display apparatus otherthan the projector 10, a rear projection (rear surface projection)-typeprojector, a liquid crystal display, an organic Electro Luminescence(EL) display, a plasma display, a cathode-ray tube (CRT) display, aSurface-conduction Electron-emitter Display (SED) or the like can beused.

In addition, respective functional portions of the projection system 1illustrated in FIG. 2 indicates functional configurations, and thespecific installation state is not particularly limited. That is, it isnot always necessary to install hardware corresponding to the respectivefunctional portions, and it is obvious that one processor can realizethe functions of the plurality of functional portions by executingprograms. In addition, a portion of the function realized by software inthe present embodiment may be realized by hardware, or a portion of thefunction realized by the hardware may be realized by software. Inaddition, the specific detailed configuration of the respective portionsin addition to the projection system 1 can be voluntarily changedwithout departing from the scope of the invention.

What is claimed is:
 1. A position detection system comprising: a lightemitting apparatus that emits detection light to a detection area fordetecting an indication position of an indicator; and a positiondetection apparatus that includes: an imaging portion that captures animage of the detection area, and a position detection portion that:detects light from the indicator based on data of the image captured bythe imaging portion, detects the indication position of the indicator inthe detection area, and determines whether the indicator is a lightemitting indicator that emits light or an indicator that does not emitlight, wherein the light emitting apparatus is turned on and offrepeatedly, and when the indication position of the indicator isdetected White the light emitting apparatus is turned off, the positiondetection portion determines that the indicator is the light emittingindicator.
 2. The position detection system according to claim 1,wherein the position detection apparatus further includes a transmittingportion that transmits a synchronization signal that indicates a timingof light emissions of the indicator.
 3. The position detection systemaccording to claim 2, wherein the timing of light emissions of the lightemitting apparatus is based on the synchronization signal.
 4. A controlmethod comprising: emitting, by a light emitting apparatus, detectionlight to a detection area for detecting an indication position of anindicator; capturing, by a position detection apparatus, an image of thedetection area; detecting, by the position detection apparatus, lightfrom the indicator based on data of the image captured by the positiondetection apparatus; detecting, by the position detection apparatus, theindication position of the indicator in the detection area; anddetermining, by the position detection apparatus, whether the indicatoris a light emitting indicator that emits light or an indicator that doesnot emit light, wherein the light emitting apparatus is turned on andoff repeatedly, and when the indication position of the indicator isdetected while the light emitting apparatus is turned off, the positiondetection portion determines the indicator is the light emittingindicator.